Process for the production of superconducting monocrystals of iron chalcogenides of general formula FeTe0.5Se0.5

The invention relates to the technology of superconducting materials, in particular, to the production of monocrystals by the method of crystallization from melts.The process for the production of superconducting monocrystals of iron chalcogenides of general formula FeTe0.5Se0.5 consists in that preliminarily the initial materials selenium and tellurium are purified by zone melting, and iron pellets are subjected to mechanical cleaning, and then is performed the loading of initial materials into an evacuated vial, melting of the mixture by heating, exposure of the molten mixture at a temperature exceeding the component most refractory phase melting temperature with subsequent cooling and quenching. At the same time, heating of mixture is carried out at a rate of 2...5°C up to 600°C, is exposed for 20...24 hours, then is performed the stepwise heating with the step of 50°C at a rate of 1°C/min and exposure between steps for 8...10 hours up to reaching the temperature of 1100°C , at which the melt is exposed for 60...72 hours, then it is cooled at a rate of 2...60°C/hour up to a temperature of 420°C, at which the material is homogenized for 70...100 hours, and then it is carried out the quenching by placing the vial in a liquid at a temperature not exceeding 0°C. To obtain monocrystals of larger dimensions the obtained monocrystals are additionally milled in oxygen-free medium containing no water vapors, are heated into an evacuated vial at a rate of 5°C/min up to a temperature of 1100°C, at which the melt is exposed for 60...72 hours, then it is cooled at a rate of 2...60°C/hour up to a temperature of 420°C, at which the material is homogenized for 70...100 hours, and then is quenched by placing the vial in a liquid with a temperature not exceeding 0°C. Invenţia se referă la tehnologia materialelor supraconductoare, în particular la obţinerea monocristalelor prin metoda cristalizării din topitură.Procedeu de obţinere a monocristalelor supraconductoare de calcogenuri de fier cu formula generală FeTe0,5Se0,5 constă în aceea că preventiv materialele iniţiale seleniul şi telurul se purifică prin topirea zonală, iar granulele de fier se curăţă mecanic, apoi se efectuează introducerea materialelor iniţiale într-o fiolă vidată, topirea încărcăturii prin încălzire, menţinerea încărcăturii topite la o temperatură, care depăşeşte temperatura de topire a fazei componentelor cu cea mai înaltă temperatură de topire, cu răcirea şi călirea ulterioară. Totodată, încălzirea